Fig. 4: Zero-temperature frequency shift as a function of pressure.
From: Topological nodal line in superfluid 3He and the Anderson theorem
Frequency shift of the NMR line in the polar phase, extrapolated from fit lines in Fig. 2b to zero temperature (points). The statistical error in the shift is smaller than point size (see Supplementary Fig. 3). The line shows value from Eq. (1) with λD = 7.5 × 10−7 selected to fit the points. The main reason for the increase of the frequency shift with pressure is the increase of Tc. Additionally, the line includes increase of Δ(0)/Tc ratio with pressure due to strong-coupling corrections accepted for the B phase29. The data points show systematically stronger pressure dependence than the line, which may indicate larger strong-coupling corrections in the polar phase compared to the B phase, see Supplementary Fig. 4.
